The present invention relates to a method and apparatus for a computer network repeater and in particular to a repeater system which provides discrete distributed modules.
Repeaters provided in computer or other networks, such as local area networks (LAN), wide area networks (WAN), telecommunications networks and the like, have typically been provided in monolithic or nondistributed fashion such as providing a single chassis or cabinet for a repeater to which the various signal sources/destinations are coupled e.g. via cables and the like. This configuration can be problematic when the space which is available for accommodating network equipment is limited and/or costly because the monolithic or undistributed repeater device will typically occupy a contiguous and relatively large portion of such space. The problem is exacerbated by the fact that repeaters (especially high-bandwidth repeaters such as repeaters configured for a bandwidth of 1 gigabit per second or more) are typically provided in substantially non-modular form, e.g. are available in a relatively few sizes (both in terms of physical size and the number of ports or connections supported). In such situations, it is impossible or infeasible for a user to be able to obtain a repeater of substantially the currently-required size. Typically, the user must employ a repeater which may be substantially larger and/or support more ports or connections, than actually required. Thus, the non-modular nature of typical repeaters means that more resources (both spatial and financial) are consumed, than necessary to achieve the required repeater functionality.
Another difficulty associated with the non-modular nature of previous repeaters is the inability to be readily reconfigured to accommodate changing conditions. For example, there may be network installations in which it would be desirable to facilitate expansion of the network e.g. as the number of users increases or other conditions change and/or to remove or isolate certain network components in other types of conditions. However, monolithic-type repeaters are included in one or a few discrete sizes on an xe2x80x9call or nothingxe2x80x9d basis. Thus, in a typical situation, a network may be configured with a repeater which is over-sized for current conditions, in anticipation of later growth, or as a result of user shrinkage.
Although it is desired to reduce the inflexibility in other disadvantageous aspects associated with undistributed and/or non-modular repeaters, it is preferred that such reduction in inflexibility should not entail an undue increase in the burden of installing, configuring or administering a network. Accordingly, it would be useful to provide a distributed and/or modular, preferably high bandwidth, repeater in which some or all features associated with installing, configuring, maintaining or administering the network are performed substantially automatically such as by automatically sensing installation or removal of repeater modules or module connections. In this regard, xe2x80x9cautomaticallyxe2x80x9d means substantially without the need for manual, human configuration or installation steps (such as setting switches and the like).
For example, preferably repeater modules are readily installed or connected (e.g. by cables) by the end user in a relatively simple xe2x80x9cplug inxe2x80x9d fashion without the need for additional manipulation, such that the modules and/or associated circuitry sense the insertion, coupling or removal and perform appropriate configuration operations. Accordingly, it would be useful to provide a (preferably high-bandwidth) network repeater which is substantially distributed and/or modular in nature.
Yet another disadvantageous aspect of nondistributed or non-modular repeaters is that malfunctioning or failed units cannot be readily isolated and/or replaced. Accordingly, it would be useful to provide a network repeater having a plurality of modules such that a failed or malfunctioning module can be readily detected, isolated, removed and/or replaced.
Network devices, including repeaters or components thereof, may operate in various states such as normal operating mode, standby mode, and the like. In some cases, such devices or components may be in an xe2x80x9cerrorxe2x80x9d or non-operating state. For most efficient implementation, it would be desirable to provide indicators such as light indicators or other indicators which can provide information regarding the state of a device or component, preferably readily perceivable when the device or component is in its normal operating position, and preferably in a relatively cost-efficient fashion.
Many components of a repeater generate significant amounts of heat which, if not properly distributed and dissipated, can lead to malfunction and/or damage. Certain repeater devices and/or components thereof, can generate electromagnetic signals which, if permitted to propagate, e.g. beyond the perimeter of the device, can lead to undesirable or impermissible levels of electromagnetic interference (EMI). Accordingly, it would be useful to provide repeater devices or components in which generation of heat and/or electromagnetic signals is properly handled, controlled or restricted. It would be particularly advantageous to handle generation of heat and/or electromagnetic signals in a cost efficient manner, such as by including one or more devices of components which are useful for handling both heat and electromagnetic signals.
A number of communication systems provide some or all data in packetized form. In the time domain, data packets are typically separated from one another by a time period referred to as the inter-packet gap (IPG). In at least some systems, some or all of the IPG is used for (at least some) processing overhead and other purposes, e.g. to accommodate variability between nodes and the network. Thus, there is a potential for loss of data or other problems if the IPG becomes too short. Accordingly, it would be desirable to provide a network repeater which can substantially avoid or reduce the probability of IPGs which are too short.
At least aspects of the present invention include a recognition of problems in previous approaches, including problems as described herein. According to an aspect of the invention, a repeater is provided which is distributed in nature. xe2x80x9cRepeater,xe2x80x9d as used in the following, can include a device, function or process which may, in some circumstances, provide full-duplex communication (e.g. bypassing the repeater core) or may otherwise differ from prior usages of xe2x80x9crepeater.xe2x80x9d In one aspect the repeater function is performed by the combined operation of two or more, repeater modules which are spaced from one another and coupled together e.g. via cables. In one embodiment, different modules of the repeater may be housed in different network switches. For example, a computer network may include a plurality of switch boxes or chassis, typically all mounted in one or more racks, often adjacent one another with the switches being coupled to network nodes such as personal computers, work stations and the like. In one embodiment, two or more, in some cases, all, of the switches include one or more regions for receiving repeater modules, with the repeater modules in different switches being coupled to one another by cables and the like. Preferably, at least some aspects of system configuration are performed automatically.
According to one aspect, each of a plurality of repeater modules provides a light pipe for conveying module indicator light information to a position readily visible in the normal module operating location, such as visible when viewing a switch front panel. Preferably the light pipe is integrally formed with (formed as part of) a module case or shell.
According to one feature, a member is coupled to a repeater module printed circuit board (PCB) in such a fashion as to receive and/or convey heat generated by PCB components and/or certain electromagnetic radiation (and preferably, both heat and electromagnetic radiation). The member preferably forms all or part of a substantially electrically conductive and thermally conductive shell or shield around all or a portion of a forward (proximal) region of a repeater module. In one embodiment, a system of vents in a repeater module case provides air flow for dissipating heat.
According to one aspect, the repeater is configured to avoid reductions in the size of the IPG between pairs of packets by identifying certain invalid or xe2x80x9ccollisionxe2x80x9d symbols and forwarding the packet without causing downstream modules to increase packet length at the expense of the IPG.
A repeater, useable for connecting switches in a data communication network, is provided in a distributed and/or modular fashion. The repeater includes a plurality of separate and distinct components or modules connected to or at least partially housed in, the various switches which the repeater modules couple. The distributed and/or modular repeater facilitates accommodating various switching or repeater needs as a network grows or contracts. A light pipe, preferably integral with a module case, conveys indicator lights to a position visible when viewing a switch front panel. A heat spreader unit receives and/or conveys heat and/or protects against undue EMI. A collision-handling state machine transmits modified collision fragments so as to avoid reduction in interpacket gaps, e.g. by downstream repeater modules.